The Syrian Observatory for Human Rights said Islamic State jihadist group has executed 2001 civilians as well as 420 of its own members in Syria since declaring its Caliphate 18 months ago.
It said on Tuesday in London that among the dead civilians were some 930 members of the Shuaitat tribe, who rose up against the jihadist organisation in 2014 after it captured their homeland in eastern Syria.
Human rights said the jihadist group has executed 420 of its own members, mainly foreign fighters, on charges of spying for foreign countries or because they were trying to escape and return home.
The observatory said victims of Islamic State’s executions in Syria also included over 1000 government troops and loyalist militiamen as well as 253 rebel fighters and rival jihadists.
It recalled that on June 29, 2014, weeks after capturing swathes of neighbouring Iraq in a lightning offensive, the organisation declared its leader Abu Bakr al-Baghdadi caliph and said he was entitled to the allegiance of all Muslims worldwide.
The observatory said the group has deliberately cultivated a reputation for brutality with graphic videos showing executions of its prisoners.
It said this was in an apparent effort to gain media attention and deter any opposition to its rule.
Islamic State has its origins in the Iraqi branch of al-Qaeda, but it split with the older jihadist organisation when Islamic State sought to subsume its Syrian front organisation, the al-Nusra Front, in 2013.
Al-Nusra’s leader, Abu Mohammed al-Jaulani, resisted the move and his organisation continues to fight alongside other rebels against the government of Syrian President Bashar al-Assad.
Islamic State, by contrast, was fighting for territory against Syrian rebels as well as Kurdish and government forces in both Iraq and Syria.
The U.S. has formed an international coalition targeting the group with air strikes as well as measures aimed at cutting its financial and arms supplies.